An impedance-based microfluidic flow cytometer uses a small channel in combination with control of the flow of fluid streams in that channel to guide cells or other particles between two or more electrodes that measure electrical impedance in the vicinity of each electrode or between pairs of electrodes. This principle has been applied in various embodiments, including several published micro flow cytometers. Note that the term flow cytometer is used loosely herein, as the apparatus can be used for the characterization of the impedance of a large variety of particles, not only cells.